算法之美_源码公布（1）

本文辑录了《算法之美——隐匿在数据结构背后的语言》（电子工业出版社2016年出版）一书第1~2章之代码（P1~P61）。全文文件夹、“45个算法”文件夹、“22个经典问题文件夹”，以及有奖捉虫活动详情请见例如以下链接：http://blog.csdn.net/baimafujinji/article/details/50484348

附录中的经典笔试、面试问题參考答案请见：

http://blog.csdn.net/baimafujinji/article/details/50484683

探秘算法世界。求索数据结构之道；汇集经典问题，畅享编程技法之趣；点拨求职热点，敲开业界名企之门。

网上书店：

京东链接：http://item.jd.com/10111000454.html

http://item.jd.com/10111372484.html

China-pub中国互动出版网：http://product.china-pub.com/4911922

亚马逊：http://www.amazon.cn/%E7%AE%97%E6%B3%95%E4%B9%8B%E7%BE%8E-%E9%9A%90%E5%8C%BF%E5%9C%A8%E6%95%B0%E6%8D%AE%E7%BB%93%E6%9E%84%E8%83%8C%E5%90%8E%E7%9A%84%E5%8E%9F%E7%90%86-%E5%B7%A6%E9%A3%9E/dp/B01AGNUIE8/ref=sr_1_8?ie=UTF8&qid=1453527399&sr=8-8&keywords=%E5%B7%A6%E9%A3%9E

电子工业出版社官方链接：http://www.phei.com.cn/module/goods/wssd_content.jsp?bookid=44441

假设你是该书的读者。请务必加算法学习群（495573865），内有很多其它资源等你，而你在读书中遇到的疑问也将得到我第一时间的解答。

很多其它关注本博客，我将陆续公布该书所有源码至本博客。

P2：C++中的原子数据类型与它们所占的存储空间

#include <iostream>

using namespace std;

int main(int argc, char** argv) {

    cout << "bool: " << sizeof(bool) << endl;
    cout << "char: " << sizeof(char) << endl;
    cout << "short: " << sizeof(short) << endl;
    cout << "int: " << sizeof(int) << endl;
    cout << "long: " << sizeof(long) << endl;
    cout << "float: " << sizeof(float) << endl;
    cout << "double: " << sizeof(double) << endl;

	return 0;
}

P25：变量与地址

#include "stdafx.h"
#pragma runtime_checks( "", off )

int _tmain(int argc, _TCHAR* argv[])
{
	int a = 97;
	int b = 98;
	int c = 99;
	return 0;
}

P29：使用指针变量

#include "stdafx.h"
#include "iostream"
#pragma runtime_checks( "", off )

using namespace std;

int _tmain(int argc, _TCHAR* argv[])
{
	unsigned int a = 5;
	unsigned int *pint = NULL;

	cout << "&a = " << &a << endl << " a = " << a << endl;
	cout << " &pint = " << &pint << endl << " pint = " << pint << endl;
	cout << " &(*pint) = " << &(*pint) << endl << endl;

	pint = &a;
	cout << "&a = " << &a << endl << " a = " << a << endl;
	cout << " &pint = " << &pint << endl << " pint = " << pint << endl;
	cout << " &(*pint) = " << &(*pint) << endl << endl;

	*pint = 10;
	cout << "&a = " << &a << endl << " a = " << a << endl;
	cout << " &pint = " << &pint << endl << " pint = " << pint << endl;
	cout << " &(*pint) = " << &(*pint) << endl << endl;

	system("PAUSE");
	return 0;
}

P32：函数的參数传递——按值传递

#include <iostream>

using namespace std;

void fun(int x)
{
	cout<< “x = ”<<x<<endl;
	x++;
	cout<< “x = ”<<x<<endl;
}

int main(int argc, char** argv) {

	int x = 0;
	cout<<"x = " <<x<<endl;
	fun(x);
	cout<<"x = " <<x<<endl;

	return 0;
}

P33：按值传递对象

#include <iostream>

using namespace std;

class Student {

	string name;
	int age;

public:
	Student() : name(""), age(0) {}

	void set_age(int age) {this->age = age;}
	int get_age() { return age;}
	void set_name(string name) {this->name = name;}
	string get_name() { return name;}
};

void increment_age(Student s) {
	s.set_age(s.get_age() + 1);
}

int main(int argc, char** argv) {

	Student s;
	s.set_name("Wumingshi");
	s.set_age(20);

	increment_age(s);

	cout << s.get_age() << endl;

	return 0;
}

P34：函数的參数传递——指针传递

#include <iostream>

using namespace std;

void fun(int* p)
{
	cout<< "*p = "<<*p<<endl;
	(*p)++;
	cout<< "*p = "<<*p<<endl;
}

int main(int argc, char** argv){
	int x = 0;
	cout<<"x = " <<x<<endl;
	fun(&x);
	cout<<"x = " <<x<<endl;
	return 0;
}

P35：函数的參数传递——引用传递

#include <iostream>

using namespace std;

void fun(int& r)
{
	cout<< "r = "<<r<<endl;
	r++;
	cout<< "r = "<<r<<endl;
}

int main(int argc, char** argv){
	int x = 0;
	cout<<"x = " <<x<<endl;
	fun(x);
	cout<<"x = " <<x<<endl;
	return 0;
}

P36：採用引用传递方式来传递指针

#include <iostream>

using namespace std;

void first_bigger(int*& p, int threshold) {

	while (*p <= threshold) {
		p++;
	}
}

int main(int argc, char** argv) {

	int numbers[] = {0, 12, 32, 44, 33, 5, 85, 45, 100, 75};
	int* result = &numbers[0];

	cout <<"Begin at: "<< *result << endl;
	first_bigger(result, 60);
	cout <<"Result is: "<< *result << endl;

	return 0;
}

P39-1：数组的使用（数组元素求和）

#include <iostream>

using namespace std;

int main(int argc, char* argv[]) {

	int a[10] = {1, 32, 65, 2, 100, 34, 33, 21, 10, 1};
	int sum = 0;

	for(int i = 0; i < 10; i++){
		sum = sum + a[i];
	}
	cout << "数组中元素的和为 " << sum<< endl;
	return 0;
}

P39-2：数组的越界訪问

#include <iostream>

using namespace std;

int main(int argc, char* argv[]) {

	int a[5] = {1, 2, 3, 4, 5};
	int b[5] = {6, 7, 8, 9, 10};

cout << b[6] << endl;
return 0;
}

P41：矩阵转置

#include <iostream>

using namespace std;

int main(int argc, char** argv) {

	int a[4][4] = {{0, 1, 2, 3}, {4, 5, 6, 7}, {8, 9, 10, 11}, {12, 13, 14, 15}};
	int i = 0;
	int j = 0;
	int tmp = 0;
	
	for(i =0; i < 4; i++)
	{
		for(; j < 4; j++)
		{
			tmp = a[i][j];
			a[i][j] = a[j][i];
			a[j][i] = tmp;
		}
		j=i+1;
	}
	
	for(i = 0; i < 4; i++)
	{
		for(j = 0; j < 4; j++)
		{
			cout<<a[i][j]<<" ";
		}
		cout<<endl;
	}

	return 0;
}

P42：数组与指针的关系

#include <iostream>

using namespace std;

int main(int argc, char* argv[]) {

	int a[10] = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9};
	int * p;
	p = &a[0];

	cout<< a[0] <<endl;
	cout<< &a[0]<<endl;
	cout<< &a<<endl;
	cout<< a <<endl;
	cout<< p <<endl;
	cout<< *p<<endl;

	return 0;
}

P43：自加运算符与指针

#include <iostream>
using namespace std;

int main(int argc, char* argv[]) {

	int a[10] = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9};
	int * p;

	p = &a[0];
	cout<< *(p++)<<endl;
	p = &a[0];
	cout<< *p++<<endl;
	p = &a[0];
	cout<< *(++p)<<endl;

	return 0;
}

P44：指针訪问多维数组

#include <iostream>

using namespace std;

int main(int argc, char* argv[]){
	int a[3][3] = {0, 1, 2, 3, 4, 5, 6, 7, 8};

	int * p;
	p = &a[0][0];

	for(int i = 0; i<9; i++)
		cout<<*p++<<endl;
	return 0;
}

P46：数组的抽象数据类型

头文件

#ifndef ARRAY_H
#define ARRAY_H

#include <iostream>

using namespace std;

const int DefaultSize = 20;

template <class Type>
class Array
{
	Type *elements;			//数组存放空间 
	int ArraySize;			//当前长度
public: 
	Array(int Size=DefaultSize);					//构造函数
	Array(const Array<Type>& x);	     				//拷贝构造函数
	~Array() {delete []elements;}		 			//析构函数
	Array<Type> & operator = (const Array<Type> & rhs);		//数组复制
	Type& operator [] ( int i );	   				//取元素值
	int Length () const { return ArraySize; }			//取数组长度
	void ReSize (int sz);	           				//扩充数组
};

template <class Type>
Array<Type>& Array<Type >::operator= (const Array<Type >& rhs)
{
	int n = rhs. ArraySize; 		// 取rhs的数组大小
	if (ArraySize != n)
	{
		delete [] elements; 		// 删除数组原有内存
		elements = new Type[n];		// 又一次分配n个元素的内存
		if (elements == NULL)		//假设分配内存不成功，输出错误信息
		{
			ArraySize = 0; 
			cerr << "存储分配错误！
" << endl;
			exit(1);
		}
		ArraySize = n;			//记录本对象的数组大小
    }
	// 从rhs向本对象复制元素
	Type* destptr = elements;
	Type* srcptr = rhs. elements;
	while (n--)
		*destptr++ = *srcptr++;
	return *this; // 返回当前对象的引用
}

template <class Type>
Array<Type> :: Array (int sz) 
{
	if ( sz <= 0 ) {
		ArraySize = 0;
		cerr << "非法数组大小" << endl;
		return; 
     }		 
	elements = new Type[sz];
	if (elements == NULL) { 
		ArraySize = 0; 
		cerr << "存储分配错误！" << endl;
		exit(1);
	}
	ArraySize = sz;
}


template <class Type>
Array<Type> :: Array (const Array<Type> & x )
{
	int n = x.ArraySize;
	ArraySize = n;
	elements = new Type[n]; 
	if ( elements == NULL ) {
		ArraySize = 0;
		cerr << "存储分配错" << endl;
		exit(1);
	}
	Type *srcptr = x.elements; 
	Type *destptr = elements; 
	while ( n-- ) * destptr++ = * srcptr++;
}

template <class Type>
Type& Array<Type> :: operator [] (int i){
	if ( i < 0 || i > ArraySize-1 ) { 
		cerr << "数组下标超界" << endl;
		exit(1);
	}
	return elements[i];					
}

template <class Type>
void Array<Type> :: ReSize (int sz) {
	if (sz >= 0 && sz != ArraySize) {
		Type * newarray = new Type[sz];			//创建新数组
		if (newarray == NULL) {
			cerr << "存储分配错" << endl;
			return;
		}
		int n = (sz <= ArraySize) ? sz : ArraySize; 	//按新的大小确定传送元素个数
		Type *srcptr = elements;			//源数组指针 
		Type *destptr = newarray;			//目标数组指针 
		while (n--) * destptr++ = * srcptr++; 
		delete [] elements;	
		elements = newarray;
		ArraySize = sz;
	}
}

#endif

測试程序

#include <iostream>
#include <iomanip>
#include "Array.h"

using namespace std;

int main(int argc, char** argv) {

	Array<int>  A(10);

	int n;
	int primecount = 0, i, j;
	
	cout << "Enter a value >= 2 as upper limit for prime numbers: ";
	cin >> n;
	A[primecount++] = 2;    // 2是一个质数,[]下标运算
	
	for(i = 3; i < n; i++) {
		if (primecount == A.Length()) A.ReSize(primecount + 10);
		if (i % 2 == 0) continue;
		j = 3;
		while (j <= i/2 && i % j != 0) j += 2;
		if (j > i/2) A[primecount++] = i;
	}
	
	for (i = 0; i < primecount; i++) {
		cout << setw(5) << A[i];
		if ((i+1) % 10 == 0)  cout << endl;
	}
	cout << endl;

	return 0;
}

P49：Z字形编排问题

请參见博文——ZigZag排列问题与经典笔试面试题目解析

（链接地址：http://blog.csdn.net/baimafujinji/article/details/50388584）

P51：大整数乘法问题

#include <iostream>
#include <memory.h>

#define SIZE 14

using namespace std;

// 返回位数为size1+size2
int* multi(int* num1, int size1, int* num2, int size2)
{
	int size = size1 + size2;
	int* ret = new int[size];
	int i = 0;

	memset(ret, 0, sizeof(int) * size);

	for (i = 0; i < size2; ++i)
	{
		int k = i;
		for (int j = 0; j < size1; ++j)
			ret[k++] += num2[i] * num1[j];
	}

	for (i = 0; i < size; ++i) 
	{
		if (ret[i] >= 10)
		{
			ret[i+1] += ret[i] / 10;
			ret[i] %= 10;
		}
	}
	return ret;
}

int main(int argc, char** argv) {
	
	int num1[SIZE] = {1,2,3,4,5,6,7,8,9,1,1,1,1,1};//第一个大整数 11111987654321
	int num2[SIZE] = {1,1,1,2,2,2,3,3,3,4,4,4,5,5};//第二个大整数 55444333222111

	int* ret = multi(num1, SIZE, num2, SIZE);

	for (int i = SIZE*2-1; i >= 0; i--)
		cout << ret[i];
	
	delete[] ret; //释放内存
	
	return 0;
}

P52：九宫格问题

#include <iostream>
#include <iomanip>
#include <memory.h>

using namespace std;

int main()
{
    cout<<"请输入幻方的大小n（n是一个大于1的奇数）：";
    int n=1;
    cin>>n;
    cout<<endl;
    int **a = new int*[n];
    for(int i=0; i<n; ++i){
	a[i]=new int[n];
	memset(a[i], 0, n*sizeof(int));	
    }

    int row=0;
    int col=n/2;
                        
    for(int i=1; i<=n*n; i++) {
        a[row][col]=i;
        row--;
        col++;
        
	if(row<0&&col>=n)
        {
            col--;
            row+=2;
        }
        else if(row<0)
        {
            row=n-1;
        }
        else if(col>=n)
        {
            col=0;
        }
        else if(a[row][col]!=0)
        {
            col--;
            row+=2;
        }
    }
    	
    for(int i=0;i<n;i++)
    {
        for(int j=0;j<n;j++)
        {
            cout<<setw(6)<<a[i][j];
        }
        cout<<endl;
    }
        
    for(int i = n; i > 0;)
        delete[] a[--i];
    delete[] a;

    return 0;	
}

P55：用new来创建对象

#include <iostream>

using namespace std;

class Point
{
	int x;
	int y;

public:

	Point()
	{ 
		x = 0;
		y = 0;
	};
	Point(int xx, int yy)
	{
		x = xx;
		y = yy;
	};
	~Point(){cout<<"END"<<endl;};

	int getX(){return x;};
	int getY(){return y;};
	void setX(int newX){x = newX;};
	void setY(int newY){y = newY;};
};

int main(int argc, char** argv) {

	Point * point1 = new Point;
	Point * point2 = new Point(3, 5);

	cout<<point1->getX()<<endl;
	cout<<point2->getX()<<endl;

	delete point1;
	delete point2;

	return 0;
}